Macrolides

ABSTRACT

A mixture comprising a poly-ene macrolide and an antioxidant. Preferably, the poly-ene macrolide is rapamycin and the antioxidant is 2,6-di-tert.-butyl-4-methylphenol. The presence of the antioxidant improves the stability of the poly-ene macrolide to oxidation.

This application is a continuation of International Application No.PCT/EP99/09521, filed Dec. 6, 1999, the contents of which areincorporated herein by reference.

The present invention relates to the stabilization of a pharmaceuticallyactive ingredient sensitive to oxidation, e.g. a poly-ene macrolide,preferably a poly-ene macrolide having immunosuppressant properties,particularly rapamycins.

The handling and storage particularly in the bulk form ofpharmaceutically active ingredients which are sensitive to oxidation isdifficult. Special handling is necessary and often theoxidation-sensitive ingredient Is stored in air-tight packaging underprotective gas. Substantial amounts of stabilizers are added during theformulating process of such pharmaceutically active ingredients.

Poly-ene macrolides have satisfactory stability properties. However, ithas now been found that their stability to oxygen may substantially beimproved by the addition of a stabilizer, e.g. an antioxidant, duringtheir Isolation step.

According to the invention, there is provided

-   1. A process for stabilizing a poly-ene macrolide comprising adding    an antioxidant to the purified macrolide, preferably at the    commencement of its isolation step.    -   This process is particularly useful for the production of a        stabilized poly-ene macrolide in bulk. The amount of antioxidant        may conveniently be up to 1%, more preferably from 0.01 to 0.5%        (based on the weight of the macrolide). Such a small amount is        referred to hereinafter as a catalytic amount.

As alternatives to the above the present invention also provides:

-   2. A mixture, e.g. a bulk mixture, comprising a poly-ene macrolide    and an anti-oxidant, preferably a catalytic amount thereof,    preferably in solid form.    -   The mixture may be in particulate form e.g. crystallized or        amorphous form. It may be In a sterile or substantially sterile        condition, e.g. in a condition suitable for pharmaceutical use.-   3. Use of a mixture as defined above in 2. In the manufacture of a    pharmaceutical composition.

Examples of poly-enes macrolides are e.g. molecules comprising doublebonds, preferably conjugated double bonds, for example such havingantibiotic and/or immunosuppressant properties, e.g. macrolidescomprising a lactam or lactone bond and their derivatives, e.g.compounds which have a biological activity qualitatively similar to thatof the natural macrolide, e.g. chemically substituted macrolides.Suitable examples include e.g. rapamycins and ascomycins. A preferredpoly-ene macrolide is a macrolide comprising at least 2 conjugateddouble bonds, e.g. 3 conjugated double bonds.

Rapamycin is a known lactam macrolide produceable, for example byStreptomyces hygroscopicus. The structure of rapamycin Is given inKessler, H. et al.; 1993; Helv. Chim. Acta, 76:117. Rapamycin hasantibiotic and immunosuppressant properties. Derivatives of rapamycinare known, e.g. 16-O-substituted rapamycins, for example as disclosed inWO 94/02136 and WO 96/41807, 40-O-substituted rapamycins, for example asdisclosed in WO 94/09010, WO 92/05179, WO 95/14023, 94/02136, WO94/02385 and WO 96/13273, all of which being incorporated herein byreference. Preferred rapamycin derivatives are e.g. rapamycins whereinthe hydroxy in position 40 of formula A illustrated at page 1 of WO94/09010 is replaced by —OR wherein R is hydroxyalkyl,hydroxyalkoxyalkyl, acylaminoalkyl or aminoalkyl, e.g.40-O-(2-hydroxy)ethyl-rapamycin, 40-O-(3-hydroxy)propyl-rapamycin, and40-O-[2-(2-hydroxy)ethoxy]ethyl-rapamycin.

Ascomycins, of which FK506 and ascomycin are the best known, formanother class of lactam macrolides, many of which have potentimmunosuppressive and anti-inflammatory activity. FK506 is a lactammacrolide produced by Streptomyces tsukubaensis. The structure of FK506is given in the Appendix to the Merck Index, 11th ed. (1989) as Item A5.Ascomycin is described e.g. In U.S. Pat. No. 3,244,592. Ascomycin.FK506, other naturally occurring macrolides having a similar biologicalactivity and their derivatives, e.g. synthetic analogues and derivativesare termed collectively “Ascomycins”. Examples of synthetic analogues orderivatives are e.g. halogenated ascomycins, e.g.33-epi-chloro-33-desoxy-ascomycin such as disclosed in EP-A427,680,tetrahydropyran derivatives. e.g. as disclosed in EP-A-626,385.

Particularly preferred macrolides are rapamycin and40-O-(2-hydroxy)ethyl-rapamycin.

Preferred antioxidants are for example 2,6-di-tert.-butyl-4-methylphenol(hereinafter BHT), vitamin E or C, BHT being particularly preferred.

A particularly preferred mixture of the invention is a mixture ofrapamycin or 40-O-(2-hydroxy)ethyl-rapamycin and 0.2% (based on theweight of the macrolide) of antioxidant, preferably BHT.

The antioxidant may be added to the poly-ene macrolide at thecommencement of the isolation steps, preferably the final isolationstep, more preferably just prior to the final precipitation step. Themacrolide is preferably in a purified state. It may be dissolved in aninert solvent and the antioxidant is added to the resulting solution,followed by a precipitation step of the stabilized macrolide, e.g. in anamorphous form or in the form of crystals. Preferably the mixture of theinvention is in amorphous form.

The resulting stabilized macrolide exhibits surprisingly an improvedstability to oxidation and its handling and storage, e.g. in bulk formprior to its further processing for example into a galenic composition,become much easier. It is particularly interesting for macrolides inamorphous form.

The macrolide stabilized according to the invention may be used as suchfor the production of the desired galenic formulation. Such formulationsmay be prepared according to methods known in the art, comprising theaddition of one or more pharmaceutically acceptable diluent or carrier,including the addition of further stabilizer if required.

Accordingly there is further provided:

-   4. A pharmaceutical composition comprising, as active Ingredient, a    stabilized mixture as disclosed above, together with one or more    pharmaceutically acceptable diluent or carrier.    -   The composition of the invention may be adapted for oral,        parenteral, topical (e.g. on the skin), ocular, nasal or        inhalation (e.g. pulmonary) administration. A preferred        composition is one for oral administration, preferably a        water-free composition when the active ingredient is a lactone        macrolide.

The pharmaceutical compositions of the invention may comprise furtherexcipients, e.g. a lubricant, a disintegrating agent, a surfactant, acarrier, a diluent, a flavor enhancer, etc. It may be in liquid form,e.g. solutions, suspensions or emulsions such as a microemulsions, e.g.as disclosed in U.S. Pat. No. 5,536,729, or in solid form, e.g.capsules, tablets, dragées, powders (including micronized or otherwisereduced particulates), solid dispersions, granulates, etc., e.g. asdisclosed in WO 97/03654, the contents of which being incorporatedherein by reference, or semi-solid forms such as ointments, gels, creamsand pastes. They are preferably adapted to be in a form suitable fororal administration. Preferably they are in solid form. Thepharmaceutical compositions of the invention may be prepared accordingto known methods, by mixing the macrolide stabilized according to theinvention with the additional ingredients under stirring; theingredients may be milled or ground and if desired compressed, e.g intotablets.

This invention is particularly interesting for rapamycin compositions inliquid or solid form. A particularly preferred composition is a soliddispersion, e.g. comprising a stabilized rapamycin according to theinvention and a carrier medium, e.g. a water-soluble polymer such ashydroxypropylmethylcellulose, e.g. as disclosed in WO 97/03654.

The compositions of the invention are useful for the indications asknown for the macrolide they contain at e.g. known dosages. For example,when the macrolide has immunosuppressant properties, e.g. rapamycin or arapamycin derivative, the composition may be useful e.g. in thetreatment or prevention of organ or tissue acute or chronic allo- orxeno-transplant rejection, autoimmune diseases or inflammatoryconditions, asthma, proliferative disorders, e.g tumors, orhyperproliferative vascular disorders, preferably in the prevention ortreatment of transplant rejection.

The amount of macrolide and of the composition to be administered dependon a number of factors, e.g. the active ingredient used, the conditionsto be treated, the duration of the treatment etc. Fr e.g. rapamycin or40-O-(2-hydroxy)ethyl-rapamycin, a suitable daily dosage form for oraladministration comprise from 0.1 to 10 mg, to be administered once or individed form.

In another aspect, this invention also provides40-O-(2-hydroxy)ethyl-rapamycin in a crystalline form, particularly in asubstantially pure form. Preferably the crystal form is characterized bythe absence or substantial absence of any solvent component; it is innon-solvate form.

40-O-(2-hydroxy)ethyl-rapamycin in crystalline form belongs to themonoclinic system. The resulting crystals have a m.p. of 146°-147° C.,especially 146.5° C. To assist identification of the new crystallineform, X-ray diffraction analysis data are provided. The conditions underwhich these data are obtained are as follows:

Temperature 293(2) K Wavelength 1.54178 Å

Space group P2₁Unit cell dimensions

-   -   a 14.378.(2) Å    -   b 11.244(1) Å    -   c 18.310(2) Å    -   β 108.58(1)°

Volume 2805.8(6) Å³ Z 2

Density (calculated) 1.134 g/cm³Absorption coefficient 0.659 mm⁻¹

F(000) 1040

Crystal size 0.59×0.11×0.03 mmθ range for data collection 2.55 to 57.20°Reflections collected 4182Independent reflections 4037 [R(Int)=0.0341]Intensity decay 32%Refinement method Full-matrix least-squares on F²

Data/restraints/parameters 3134/1/613 Goodness-of-fit on F² 1.055

Final R Indices [I>2 sigma(I)] R₁=0.0574, wR₂=0.1456Largest diff. peak and hole 0.340 and −0.184 e/Å³

40-O-(2-hydroxy)ethyl-rapamycin in crystalline form may be prepared bydissolving the amorphous compound in a solvent e.g. ethyl acetate andadding an aliphatic hydrocarbon C_(n)H_(2n+2) (n=5, 6 or 7). Afteraddition of the hydrocarbon, the resulting mixture may be warmed e.g. ata temperature of 25 to 50° C. e.g. up to 30-35° C. Storing of theresulting mixture may conveniently take place at a low temperature, e.g.below 25° C., preferably from 0 to 25° C. The crystals are filtered anddried. Heptane is preferred as an aliphatic hydrocarbon. If desired,nucleation procedures may be commenced e.g. by sonication or seeding.

The present invention also provides a process for purifying40-O-(2-hydroxy)ethyl-rapamycin comprising crystallizing40-O-(2-hydroxy)ethyl-rapamycin from a crystal bearing medium, e.g. asdisclosed above, and recovering the crystals thus obtained. The crystalbearing medium may include one or more components in addition to thoserecited above. A particularly suitable crystal bearing medium has beenfound to be one comprising ca. 2 parts ethyl acetate and ca. 5 partsaliphatic hydrocarbon, e.g. heptane.

40-O-(2-hydroxy)ethyl-rapamycin in crystalline form has been found topossess in vitro and in vivo immunosuppressive activity comparable tothat of the amorphous form. In the localized GvHD, maximal inhibition(70-80%) of lymph node swelling is achieved with a dosage of 3 mg with40-O-(2-hydroxy)ethyl-rapamycin in crystalline form.

40-O-(2-hydroxy)ethyl-rapamycin may be useful for the same Indicationsas known for the amorphous compound, e.g. to prevent or treat acute andchronic allo- or xeno-transplant rejection, autoimmune diseases orinflammatory conditions, asthma, proliferative disorders, e.g tumors, orhyperproliferative vascular disorders, e.g as disclosed in WO 94/09010or in WO 97/35575, the contents thereof being incorporated herein byreference. In general, satisfactory results are obtained on oraladministration at dosages on the order of from 0.05 to 5 or up to 20mg/kg/day, e.g. on the order of from 0.1 to 2 or up to 7.5 mg/kg/dayadministered once or, in divided doses 2 to 4× per day. Suitable dailydosages for patients are thus on the order of up to 10 mg., e.g. 0.1 to10 mg.

40-O-(2-hydroxy)ethyl-rapamycin in crystalline form may be administeredby any conventional route, e.g. orally, for example tablets or capsules,or nasally or pulmonary (by Inhalation). It may be administered as thesole active Ingredient or together with other drugs, e.g.immunosuppressive and/or immunomodulatory and/or anti-inflammatoryagents, e.g. as disclosed in WO 94/09010.

In accordance with the foregoing, the present invention also provides:

-   5. A method for preventing or treating acute or chronic allo- or    xeno-transplant rejection, autoimmune diseases or inflammatory    conditions, asthma, proliferative disorders, or hyperproliferative    vascular disorders, in a subject in need of such treatment, which    method comprises administering to said subject a therapeutically    effective amount of 40-O-(2-hydroxy)ethyl-rapamycin in crystalline    form;-   6. 40-O-(2-hydroxy)ethyl-rapamycin in crystalline form for use as a    pharmaceutical; e.g. in a method as disclosed above;-   7. A pharmaceutical composition comprising    40-O-(2-hydroxy)ethyl-rapamycin in crystalline form together with a    pharmaceutically acceptable diluent or carrier therefor;-   8. A kit or package for use in immunosuppression or inflammation,    including a pharmaceutical composition as disclosed above and a    pharmaceutical composition comprising an immunosuppressant or    immunomodulatory drug or an antiinflammatory agent.

The following examples illustrate the invention without limiting it.

EXAMPLE 1 Crystallisation

0.5 g amorphous 4-O-(2-hydroxy)ethyl-rapamycin is dissolved in 2.0 mlethyl acetate at 40° C. 5.0 ml heptane is added and the solution becomes“milky”. After warming to 30° C., the solution becomes clear again. Uponcooling to 0° C. and with scratching an oil falls out of the solution.The test tube is closed and stored at 10° C. overnight. The resultingwhite voluminous solid is then filtered and washed with 0.5 ml of amixture of ethyl acetate/hexane (1:2.5) and the resulting crystals aredried at 40° C. under 5 mbar for 16 hours.40-O-(2-hydroxy)ethyl-rapamycin in crystalline form having a m.p. of146.5° C. is thus obtained.

Crystallisation at a larger scale may be performed as follows:

250 g amorphous 40-O-(2-hydroxy)ethyl-rapamycin is dissolved in 1.0 lethyl acetate under argon with slow stirring. This solution is heated at30° C. and then during 45 minutes, 1.5 l heptane is added dropwise. 0.25g of seed crystals prepared as disclosed above are added under the sameconditions in portions. The mixture is further stirred at 30° C. over aperiod of 2 hours and the crystallisation mixture is cooled to 25° C.over 1 hour and then to 10° C. for 30 minutes and filtered. The crystalsare washed with 100 ml of a mixture ethyl acetate/hexane (2:3).Subsequent drying is performed at 50° C. and ca 5 mbar. m.p. 146.5° C.

-   IR in KBr: 3452, 2931, 1746, 1717, 1617, 1453, 1376, 1241, 1191,    1163, 1094, 1072, 1010, 985, 896 cm⁻¹

Single X-ray structure with coordinates are indicated in Tables 1 to 3below.

EXAMPLE 2 Production of Stabilized 40-O-(2-hydroxy)ethyl-rapamycin

100 g 40-O-(2-hydroxy)ethyl-rapamycin are dissolved in 600 l abs.ethanol. After addition of 0.2 g BHT, the resulting solution is addeddropwise with stirring to 3.01 water within 1 hour. The resultingsuspension is stirred for an additional 30 minutes. Filtration withsubsequent washing (3×200 ml water/ethanol at a v/v ratio of 5:1)results in a moist white product which is further dried under vacuum (1mbar) at 30° C. for 48 hours. The resulting dried product contains 0.2%(w/w) BHT.

The resulting product shows improved stability on storage. The sum ofby-products and degradation products in % after 1 week storage are asfollows:

Compound 50° C. in open flask

Ex. 2 (0.2% BHT) 1.49 Without BHT >10

The procedure of above Example may be repeated but using, as activeingredient, rapamycin.

TABLE 1 Atomic coordinates and equivalent isotropic displacementparameters (Å²) (U(eq) is defined as one third of the trace of theorthogonalized Uij tensor) x/a y/b z/c U(eq) C(1) .9065(6) .0121(9).5077(5) .060(2) O(1) .9239(4) −.0736(6) .5482(4) .076(2) C(2) .8041(5).0615(8) .4625(4) .060(2) C(3) .7847(7) .1748(10) .4984(6) .087(3) C(4).7627(7) .1515(10) .5725(7) .098(3) C(5) .6795(7) .0653(11) .5610(6).094(3) C(6) .7005(6) −.0496(9) .5256(5) .074(3) N(7) .7272(4) −.0269(6).4567(4) .059(2) C(8) .6781(5) −.0693(7) .3883(5) .055(2) O(8) .6965(4)−.0432(6) .3287(3) .074(2) C(9) .5940(6) −.1566(8) .3784(5) .056(2) O(9).6074(4) −.2513(6) .4074(4) .084(2) C(10) .4962(5) −.1136(8) .3223(5).057(2) O(10) .5045(4) −.1009(6) .2486(3) .075(2) C(11) .4079(6)−.1951(8) .3160(5) .068(3) C(11M) .4107(7) −.3114(9) .2776(6) .088(3)C(12) .3135(6) −.1252(10) .2738(6) .088(3) C(13) .3099(6) −.0061(10).3115(7) .099(4) C(14) .4002(6) .0651(9) .3156(6) .078(3) O(14) .4868(4)−.0019(5) .3559(3) .065(2) C(15) .4070(6) .01811(10) .3592(6) .082(3)C(16) .4953(7) .2564(8) .3624(6) .079(3) O(16) .4841(5) .3639(6).4015(4) .095(2) C(16M) .5697(8) .4308(10) .4288(7) .102(3) C(17).5056(6) .2802(9) .2841(6) .073(3) C(17M) .4268(7) .3541(11) .2307(6).103(4) C(18) .5806(7) .2368(10) .2680(6) .079(3) C(19) .6018(7).2458(11) .1964(6) .092(3) C(20) .6768(8) .1937(12) .1809(6) .097(3)C(21) .7032(8) .2069(13) .1094(7) .111(4) C(22) .7771(8) .1565(15).0948(7) .121(5) C(23) .8086(8) .1781(16) .0240(6) .128(5) C(23M).7254(9) .2152(23) −.0474(7) .184(9) C(24) .8912(8) .2643(18) .0406(6).140(6) C(25) .9826(9) .2329(20) .1069(6) .141(6) C(25M) 1.0348(12).1245(20) .0884(8) .178(8) C(26) 1.0512(10) .3412(22) .1293(7) .157(8)O(26) 1.1132(8) .3601(21) .0998(7) .281(11) C(27) 1.0375(8) .4278(16).1891(7) .118(5) O(27) 1.0877(7) .5366(13) .1901(7) .185(5) C(27M)1.0445(17) .6202(22) .1382(13) .256(13) C(28) 1.0824(7) .3750(11).2699(6) .091(3) O(28) 1.1827(4) .3501(7) .2818(4) .108(2) C(29)1.0329(7) .2733(10) .2922(5) .073(3) C(29M) .9318(6) .2995(10) .2984(6).094(3) C(30) 1.0764(7) .1700(10) .3100(5) .077(3) C(31) 1.0376(7).0581(10) .3340(5) .081(3) C(31M) 1.0198(9) −.0385(13) .2723(7) .124(4)C(32) 1.1046(7) .0210(10) .4103(6) .079(3) O(32) 1.1436(7) −.0747(9).4183(5) .132(3) C(33) 1.1271(6) .1025(9) .4776(5) .071(3) C(34)1.0764(5) .0601(8) .5342(5) .062(2) O(34) .9735(3) .0853(5) .4967(3).071(2) C(35) 1.1115(5) .1217(9) .6132(5) .064(2) C(35M) 1.1060(7).2562(10) .6069(6) .092(3) C(36) 1.2149(6) .0757(9) .6578(5) .072(3)C(37) 1.2650(6) .1298(9) .7370(5) .074(3) C(38) 1.2091(7) .1198(14).7935(5) .110(4) C(39) 1.2680(9) .1650(16) .8735(6) .128(5) O(39)1.2082(8) .1584(20) .9206(6) .243(9) C(39M) 1.2099(20) .2512(47).9702(17) .498(36) C(40) 1.3640(9) .0982(13) .9048(6) ..0116(4) O(40)1.4177(7) .1412(10) .9790(5) .151(4) C(41) 1.4221(7) .1138(13) .8506(6).110(4) C(42) 1.3653(6) .0697(11) .7702(5) .096(3) C(43) 1.4272(14).0621(20) 1.0408(9) .171(7) C(44) 1.5146(20) −.0307(24) 1.0549(10).238(12) O(45) 1.4956(12) −.1215(13) .9899(7) .215(5)

TABLE 2 Bond lengths (Å) C(1)-O(1) 1.193(10) C(1)-O(34) 1.329(10)C(1)-C(2) 1.545(11) C(2)-N(7) 1.465(10) C(2)-C(3) 1.500(13) C(3)-C(4)1.511(14) C(4)-C(5) 1.502(13) C(5)-C(6) 1.518(14) C(6)-N(7) 1.453(10)N(7)-C(8) 1.315(9) C(8)-O(8) 1.237(9) C(8)-C(9) 1.523(11) C(9)-O(9)1.178(9) C(9)-C(10) 1.532(11) C(10)-O(10) 1.398(9) C(10)-O(14) 1.425(10)C(10)-C(11) 1.540(11) C(11)-C(11M) 1.491(13) C(11)-C(12) 1.546(12)C(12)-C(13) 1.51(2) C(13)-C(14) 1.506(13) C(14)-O(14) 1.441(10)C(14)-C(15) 1.516(14) C(15)-C(16) 1.511(12) C(16)-O(16) 1.439(11)C(16)-C(17) 1.512(14) O(16)-C(16M) 1.392(11) C(17)-C(18) 1.301(12)C(17)-C(17M) 1.491(13) C(18)-C(19) 1.441(14) C(19)-C(20) 1.333(14)C(20)-C(21) 1.48(2) C(21)-C(22) 1.30(2) C(22)-C(23) 1.52(2) C(23)-C(24)1.49(2) C(23)-C(23M) 1.52(2) C(24)-C(25) 1.52(2) C(25)-C(25M) 1.53(2)C(25)-C(26) 1.54(3) C(26)-O(26) 1.20(2) C(26)-C(27) 1.53(2) C(27)-O(27)1.42(2) C(27)-C(28) 1.533(14) O(27)-C(27M) 1.34(2) C(28)-O(28) 1.415(10)C(28)-C(29) 1.471(14) C(29)-C(30) 1.311(13) C(29)-C(29M) 1.523(12)C(30)-C(31) 1.497(14) C(31)-C(32) 1.482(13) C(31)-C(31M) 1.53(2)C(32)-O(32) 1.201(11) C(32)-C(33) 1.487(13) C(33)-C(34) 1.521(11)C(34)-O(34) 1.447(9) C(34)-C(35) 1.537(11) C(35)-C(35M) 1.517(13)C(35)-C(36) 1.540(11) C(36)-C(37) 1.525(12) C(37)-C(38) 1.503(11)C(37)-C(42) 1.532(12) C(38)-C(39) 1.526(14) C(39)-O(39) 1.399(13)C(39)-C(40) 1.51(2) O(39)-C(39M) 1.38(4) C(40)-O(40) 1.417(13)C(40)-C(41) 1.50(2) O(40)-C(43) 1.41(2) C(41)-C(42) 1.521(14)C(43)-C(44) 1.59(3) C(44)-O(45) 1.52(2)

TABLE 3 Bond angles (°) O(1)-C(1)-O(34) 125.1(7) O(1)-C(1)-C(2) 126.8(8)O(34)-C(1)-C(2) 108.0(8) N(7)-C(2)-C(3) 111.5(6) N(7)-C(2)-C(1) 111.3(7)C(3)-C(2)-C(1) 110.4(7) C(2)-C(3)-C(4) 111.6(9) C(5)-C(4)-C(3) 111.8(9)C(4)-C(5)-C(6) 110.6(7) N(7)-C(6)-C(5) 111.4(8) C(8)-N(7)-C(6) 123.5(7)C(8)-N(7)-C(2) 118.6(7) C(6)-N(7)-C(2) 117.3(6) O(8)-C(8)-N(7) 123.6(7)O(8)-C(8)-C(9) 115.6(7) N(7)-C(8)-C(9) 120.8(8) O(9)-C(9)-C(8) 121.3(7)O(9)-C(9)-C(10) 124.8(8) C(8)-C(9)-C(10) 113.6(7) O(10)-C(10)-O(14)112.1(7) O(10)-C(10)-C(9) 109.7(6) O(14)-C(10)-C(9) 100.5(6)O(10)-C(10)-C(11) 108.1(6) O(14)-C(10)-C(11) 111.6(6) C(9)-C(10)-C(11)114.9(7) C(11M)-C(11)-C(10) 114.3(7) C(11M)-C(11)-C(12) 111.2(8)C(10)-C(11)-C(12) 107.9(7) C(13)-C(12)-C(11) 111.9(8) C(14)-C(13)-C(12)109.9(9) O(14)-C(14)-C(13) 109.8(8) O(14)-C(14)-C(15) 106.2(7)C(13)-C(14)-C(15) 113.2(8) C(10)-O(14)-C(14) 115.1(6) C(16)-C(15)-C(14)114.5(7) O(16)-C(16)-C(15) 105.4(7) O(16)-C(16)-C(17) 112.5(8)C(15)-C(16)-C(17) 113.4(8) C(16M)-O(16)-C(16) 114.0(7)C(18)-C(17)-C(17M) 124.9(9) C(18)-C(17)-C(16) 119.2(9)C(17M)-C(17)-C(16) 115.9(8) C(17)-C(18)-C(19) 127.7(10)C(20)-C(19)-C(18) 125.6(11) C(19)-C(20)-C(21) 126.6(11)C(22)-C(21)-C(20) 126.3(12) C(21)-C(22)-C(23) 126.0(13)C(24)-C(23)-C(23M) 111(2) C(24)-C(23)-C(22) 111.4(10) C(23M)-C(23)-C(22)114.2(10) C(23)-C(24)-C(25) 116(2) C(24)-C(25)-C(25M) 111.7(14)C(24)-C(25)-C(26) 110(2) C(25M)-C(25)-C(26) 111.9(12) O(26)-C(26)-C(27)120(2) O(26)-C(26)-C(25) 122(2) C(27)-C(26)-C(25) 118.5(12)O(27)-C(27)-C(26) 112.2(12) O(27)-C(27)-C(28) 105.4(12)C(26)-C(27)-C(28) 109.5(12) C(27M)-O(27)-C(27) 118.5(14)O(28)-C(28)-C(29) 111.3(9) O(28)-C(28)-C(27) 108.7(8) C(29)-C(28)-C(27)118.4(10) C(30)-C(29)-C(28) 121.5(9) C(30)-C(29)-C(29M) 122.9(10)C(28)-C(29)-C(29M) 115.4(9) C(29)-C(30)-C(31) 128.7(9) C(32)-C(31)-C(30)108.8(8) C(32)-C(31)-C(31M) 113.7(10) C(30)-C(31)-C(31M) 111.8(8)O(32)-C(32)-C(31) 120.3(11) O(32)-C(32)-C(33) 118.8(10)C(31)-C(32)-C(33) 120.8(9) C(32)-C(33)-C(34) 110.2(8) O(34)-C(34)-C(33)104.8(6) O(34)-C(34)-C(35) 109.8(6) C(33)-C(34)-C(35) 114.5(7)C(1)-O(34)-C(34) 119.2(7) C(35M)-C(35)-C(34) 112.6(8) C(35M)-C(35)-C(36)113.2(8) C(34)-C(35)-C(36) 108.6(7) C(37)-C(36)-C(35) 116.9(8)C(38)-C(37)-C(36) 115.6(7) C(38)-C(37)-C(42) 109.6(8) C(36)-C(37)-C(42)107.5(8) C(37)-C(38)-C(39) 112.5(8) O(39)-C(39)-C(40) 113.9(13)O(39)-C(39)-C(38) 108.2(10) C(40)-C(39)-C(38) 111.0(11)C(39)-O(39)-C(39M) 119(2) O(40)-C(40)-C(41) 110.3(10) O(40)-C(40)-C(39)110.2(12) C(41)-C(40)-C(39) 108.9(10) C(43)-O(40)-C(40) 115.9(12)C(40)-C(41)-C(42) 111.2(9) C(41)-C(42)-C(37) 112.8(9) O(40)-C(43)-C(44)114(2) O(45)-C(44)-C(43) 112.2(14)

1-13. (canceled)
 14. A solid mixture comprising a polyene macrolide andan antioxidant, wherein the polyene macrolide is a rapamycin derivativeor an ascomycin and the antioxidant is present in an catalytic amount.15. The mixture according to claim 14, wherein the antioxidant ispresent in an amount of up to 1% based on the macrolide weight.
 16. Themixture according to claim 15, wherein the antioxidant is present in anamount of 0.01 to 0.5% based on the macrolide weight.
 17. The mixtureaccording to claim 16, wherein the antioxidant is present in an amountof 0.2% based on the macrolide weight.
 18. The mixture according toclaim 14, wherein the antioxidant is selected from the group consistingof vitamin E, vitamin C, 2,6-di-tert.-butyl-4-methylphenol (BHT), andcombinations thereof.
 19. The mixture according to claim 14, wherein theascomycin is selected from the group consisting of ascomycin, FK-506, anhalogenated ascomycin and a tetrahydropyran derivative.
 20. The mixtureaccording to claim 14, wherein the ascomycin is33-epi-chloro-33-desoxy-ascomycin or a tetrahydropyran derivativethereof.
 21. A pharmaceutical composition comprising, as activeingredient, the mixture according to claim 14 together with one or morepharmaceutically acceptable carriers or diluents.
 22. The pharmaceuticalcomposition of claim 21 for oral administration.
 23. A process forstabilizing a polyene macrolide, wherein the polyene macrolide is arapamycin derivative or an ascomycin, said process comprising a)dissolving pure rapamycin derivative or pure ascomycin in an inertsolvent, b) adding an antioxidant to the resulting solution in amount ofup to 1% based on the rapamycin derivative or ascomycin weight, and c)isolating the resulting mixture of the rapamycin derivative or theascomycin and the antioxidant.
 24. The process of claim 23, wherein theascomycin is selected from the group consisting of ascomycin, FK-506, anhalogenated ascomycin and a tetrahydropyran derivative.
 25. The processof claim 23, wherein the ascomycin is 33-epi-chloro-33-desoxy-ascomycinor a tetrahydropyran derivative thereof.
 26. The process of claim 23,wherein the antioxidant is selected from the group consisting of vitaminE, vitamin C, 2,6-di-tert.-butyl-4-methylphenol (BHT) and combinationsthereof.
 27. The process of claim 23, wherein the antioxidant is presentin an amount of up to 1% based on the macrolide weight.
 28. The processof claim 27, wherein the antioxidant is present in an amount of from0.01 to 0.5% based on the macrolide weight.
 29. The process of claim 28,wherein the antioxidant is present in an amount of 0.2% based on themacrolide weight.
 30. A method for preventing or treating acute orchronic allo- or xeno-transplant rejection, autoimmune diseases orinflammatory conditions, asthma, proliferative disorders, orhyperproliferative vascular disorders in a subject in need of suchtreatment, which method comprises administering to said subject atherapeutically effective amount of the solid mixture according to claim14.
 31. A method for preventing or treating acute or chronic allo- orxeno-transplant rejection, autoimmune diseases or inflammatoryconditions, asthma, proliferative disorders, or hyperproliferativevascular disorders, in a subject in need of such treatment, which methodcomprises administering to said subject a therapeutically effectiveamount of the pharmaceutical composition according to claim 21.